Openings or gaps in interior or exterior walls of a building, such as joint portions or holes, are covered by mortar, a sealant, or a foaming agent, for the purpose of satisfying at least one of water resistance, fire resistance, and sound insulation.
As an example of the above, Patent Literature (PTL) 1 discloses a two-component aerosol-type flame-retardant polyisocyanurate foam, characterized in that an isocyanate component that comprises an organic polyisocyanate and a propellant as main components and that is inserted in an aerosol can is reacted with a polyol component that comprises a polyol, a trimerization catalyst, and a propellant as main components and that is inserted in another aerosol can, so as to achieve the equivalent ratio of NCO/OH of 1.5 to 5.0. Also, Patent Literature (PTL) 2 discloses a multi-component, on-site foaming system for producing polyurethane foams on site for building purposes, with a polyisocyanate component (A) and a polyol component (B), which are in separate containers, wherein, aside from the polyisocyanate component (A) and the polyol component (B), further components (C) and (D) are contained in a spatially separate form, with the components, upon being mixed, forming an interpenetrating polymeric network of foamed polyurethane and at least one further polymer.